Hello. I'm sure this has probably being asked before, however I couldnt find any suggestions... probably not looking hard enough.

What is the best way to mount a springer on a Defender. I have a side vehicle mount, which i was gonna fit on the back of the car, on the ali roof. Do i simply just drill the holes and bolt the cables to it... or do i need to treat the aluminium, or do i need to get sealent. If so, what is the best product to use. I believe its the PSM-1 Mount

if its a basr loaded springer the use a mirror arm mount on a roof bar as they tend to pick up a lot of reflection from the body work when mounted on the side or change the antenna to a top loaded one like a dv 27